Rans-based analysis of hull spacing effects on the resistance and seakeeping of the delft 372 catamaran

This study numerically investigates the effects of hull spacing on the seakeeping performance of a high-speed catamaran using Reynolds-Averaged Navier–Stokes (RANS) simulations with the Volume of Fluid (VOF) method. The Delft 372 catamaran is used as a benchmark geometry, and simulations are carried out for spacing ratios (s/L = 0.167, 0.233 and 0.333) at Froude numbers (Fr) of 0.3, 0.5 and 0.7. Under calm water conditions, wider spacing results in lower total resistance and reduced dynamic trim, particularly at higher speeds, while at lower Fr, the spacing effect is insignificant. In regular waves, hull spacing has a more pronounced influence at low Fr, with no clear trend at higher Fr. The configuration with s/L = 0.333 minimizes total resistance. At low Fr (0.3), increased spacing suppresses peak heave and pitch responses near resonance. At higher Fr, larger spacing yields lower resistance, while vertical motion differences remain minor.